Compression & Spark Results 1988 Force 125hp

[Justinde]

HI All

I did a compression test today ( 125 not revving past about 3800rpm) and the results are as follows- top to bottom:

1: 120 p.s.i
2: 120 p.s.i
3: 130 p.s.i
4: 120 p.s.i

Spark is excellent on all plugs.

I did notice something with the throttle, however.

When the boat was stopped, in the garage, not running etc, I pushed the throttle as far as possible from the remote control, went back to the engine, and the carbies still had at least another 10mm of throttle available. It makes sense to me that full throttle is full throttle, and it appears that my engine is getting to about 3/4 throttle. Before I adjust anything, I wanted to ask you all if this was the ' normal operating range' for the throttle, and will not be effecting my speed at all, or should I get the throttle to open wide up to get the max out of my engine.

You guys are such a great help- thank you in advance.

 

[jerryjerry05]

Re: Compression & Spark Results 1988 Force 125hp

Take the control cables off. Then move the throttle forward.See it the butterflys open all the way.
It sounds like the shifter might need adjusting.Do a link and sinc.
If that isin't the problem.Then the prop might be the wrong size.
What size is the one on there.Even with the wrong prop you should do better than 4000.J

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Hey Jerry

I dont know the prop that is actually on the boat, other than it is alloy. The stainless prop I have has no identification on it other than 'p509' stamped on it, which does not help.

I will do the throttle cables today, and when I get her on the water again I'll report back. If I get a chance, I will remove the current prop and inspect for any ID.

Otherwise, I might have to take measurmments

CHeers

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Hey Jerry/All

I just removed the ' air filter' cover, and did the same. The butterfies do not open 100%, maybe 3/4, as I suspected. When I adjust this ( I have the clymers manual but...) should I also be concerned about the timing? The dizzy turns to advance with more throttle, but do I need to do the timing AND throttle together. I dont know if the timing is advanced enough for full throttle!!

Reading Clymers now, just wnted some practical experience help.

Cheers again

 

[shytownborn]

Re: Compression & Spark Results 1988 Force 125hp

do a link & sync first, the butterflies should be positioned at 100 per cent not 3/4 , timing shouldnt change unless you moved the adjustment screw. theres a big difference in performance from 3/4 to 100 percent

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Thanks Shytown

Just to elaborate- and I'll post some pics MAYBE tonight ( its NYE here!!), but, definatley 3/4 throttle at best. I just wanted to know, and again, I have the Clymers, but how do I do a ' Link & Sync". I have been looking at the Clymers, but I cannot see an adjustment for the throttle, or throttle cam. I can see the carb adjustments for fuel mix, etc, just not for the remote throttle. Any help appreciated.

Promise when its done there will be a youtube post of my beast!

Cheers and Happy New Years from Sydney.

Justin

 

[jerryjerry05]

Re: Compression & Spark Results 1988 Force 125hp

Top sticky!!Look at the top of the threads for a linc and sinc..
DON"T touch the timing rod or screws.
Like I said remove all the cables,then see if it goes farther.The towershaft is the place to adjust the idle.The roller cam on the linkage is another,the linkage with the rod and screws is another.Check the connecting pieces as they are plastic and break.They might come loose under pressure. You will need to shift it into gear to move the throttle.
Then move the throttle while it's unhooked see if it will go as far as the linkage.

Tell you what I'll do.
You pay for a ticket for the wife and I. We'll come down and help.I'll even bring any parts we need.

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Jerry & Co

You guys are always welcome here- so long as I can land on your doorstep too!!

My wife IS a travel agent, so, do you need tickets, a place to stay, somewhere to fish?

CHeers & happy new year

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

I will follow the sticky on carb sync etc, but what about remote shift cable adjustment? Nothing in my book about it, and mine was a little stiff, and I would like to adjust it so that there is not just 10mm between full throttle and zero throttle. How do I do that?

 

[jerryjerry05]

Re: Compression & Spark Results 1988 Force 125hp

Now your getting into shifters and making sure that you have the right one.
Did it come with the boat? Was it replaced with something else?
Post some pics.Look on the underside to make sure it's for a Force.
If the shifter is stiff then unhook the cables and see what's stiff.The shifter can be greased.The cables can be lubed as a temporary measure.They will need to be replaced.
The shifter is set at the factory to match the requirements of the motor.
Once you start trying to change the "throw" or length of the movement you will NEVER get it to shift or accelerate right.

Like I said post some pics.J

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Just finished the throttle adjustment The shifter is a US Marine, and came with the boat originally. Although it 'looks' like the throttle goes from 3/4 to full throttle in about 10mm, doesn't necesarily mean that is true on the water. I am taking her for a run tomorrow and will report back. Heck, I may even post a video of it on youtube! The prop that is on the boat is a 13 inch diametre, 19 inch pitch. The Stainless Steel one I have is a mystery. It fits on the spool, however, it doesnt quite tighten properly. Needs a washer ( maybe 1/4 inch) to fit 100%. I will run it with the alloy prop tomorrow and get back to you all. I may just end up selling the S/Steel one, as Jerry pointed out, they have no give if I hit bottom, it could be a potential massive repair. I may stick to alloy props.

Cheers all

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Just took it out on the water. Goes extremely well now after throttle adjustment. 42mph indicated. When I furst took her out it was 30mph indicated ( thereabouts) at 3800. But, the tacho is definatly stuffed. 42mph, engine purring but sounding every bit WOT, and tacho showing 2500! I have a spare but it is an OMC tacho, sounds dumb but that won't make a difference will it? Also, a hole shot start she coughed a spluttered a bit. No complaints, because with the wife and family on board, thats the last thing I need to be doing, but any ideas on this either?

Cheers

 

[jerryjerry05]

Re: Compression & Spark Results 1988 Force 125hp

Definatly needs a tach.Try the connections.Even tap on the tach.Sometimes this helps.
Try the OMC tach.You might get lucky and it will work.
They sell a tach that's calle a Tiny Tach. Just hook it up and go.Real simple.I bought mine from a Mercury dealer(# 79-859000a 1) a long time ago,so I don't remember how much it costs. Glad it's running better.J

 

[Frank Acampora]

Re: Compression & Spark Results 1988 Force 125hp

Look at the sticky about linc and sync again. It explains carb settings. On a hole shot: Too lean and she will "sag" then pick-up/. Too rich and she will "Burble" or sputter then clean herself out and accelerate. Better to be too rich than too lean! OMC tach will NOT work. You need a special tach for mercury and Force engines with a 20 pole stator. Tiny tach will work if induction is attached to one plug wire.

 

[Justinde]

Re: Compression & Spark Results 1988 Force 125hp

Frank & Jerry- Welcome in Sydney Australia ANYTIME, so long as you want to come fishing or skiing on Botany Bay! I will get the correct Merc/Force Tacho and report back...... Sounds like the engine is doing a genuine 5000-5500 rpm- just from my experience, but a tacho will help. I love his forum. Will keep tuning and evolving the Force 125 as I go. By the Way ( BTW) anyone know where I can get some retro Force 125 engine cover decals?